Tumor Response Kinetics after Schedule-Dependent Paclitaxel Chemoradiation Treatment for Inoperable Non-small Cell Lung Cancer: A Model for Low-Dose Chemotherapy Radiosensitization
Poor local disease control remains a major obstacle for inoperable non-small cell lung cancer (NSCLC) after radiotherapy. We previously reported results of a phase I/II clinical study based on preclinical investigations of paclitaxel radiation interactions for inoperable locally advanced NSCLC, which yielded remarkable local tumor responses and durable in-field tumor control using schedule-dependent low-dose paclitaxel for radiosensitization. Given our unique results, we analyzed the tumor response kinetics and conducted a statistical modeling of tumor response to characterize this regimen.
A total of 104 chest CT scans from 27 patients treated in the clinical trial were evaluated. Tumor volumes were calculated by three-dimensional measurements of pretreatment and serial post-therapy CT scans. A nonlinear mixed effects model was used to model response kinetics.
The average tumor volume reduction at 1 month post-therapy was 69.9 +/- 22.6% (standard deviation), and was 80.6 +/- 17.9% at the last follow-up. The nonlinear mixed effects model predicts that tumor volume will ultimately shrink by at least 75% for more than 75% of patients treated by this regimen. The model also suggests that maximum shrinkage is reached within 2 months after treatment.
Tumor volume response kinetics revealed a rapid shrinkage of gross tumors using schedule-dependent pulsed low-dose paclitaxel radiosensitization. This is contrary to the protracted tumor regression process observed in radiation alone or other chemoradiation combinations. Statistical modeling may prove useful in characterizing and comparing different therapeutic regimens.
Available from: Paolo Ubezio
- "Understanding lung tumor volume changes during radiotherapy may one day help radiation oncologists optimize dose fractions and radiosensitizing strategies for individual patients. A small number of studies have described lung tumor volume changes during conventionally fractionated external beam radiotherapy     . Lung tumor changes during hypofractionated radiotherapy, especially when delivered in short courses (≤2 weeks), are less well understood. "
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ABSTRACT: . To characterize the lung tumor volume response during conventional and hypofractionated radiotherapy (RT) based on diagnostic quality CT images prior to each treatment fraction.
. Out of 26 consecutive patients who had received CT-on-rails IGRT to the lung from 2004 to 2008, 18 were selected because they had lung lesions that could be easily distinguished. The time course of the tumor volume for each patient was individually analyzed using a computer program.
. The model fits of group L (conventional fractionation) patients were very close to experimental data, with a median Δ% (average percent difference between data and fit) of 5.1% (range 3.5–10.2%). The fits obtained in group S (hypofractionation) patients were generally good, with a median Δ% of 7.2% (range 3.7–23.9%) for the best fitting model. Four types of tumor responses were observed—Type A: “high” kill and “slow” dying rate; Type B: “high” kill and “fast” dying rate; Type C: “low” kill and “slow” dying rate; and Type D: “low” kill and “fast” dying rate.
. The models used in this study performed well in fitting the available dataset. The models provided useful insights into the possible underlying mechanisms responsible for the RT tumor volume response.
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ABSTRACT: The associations between B-cell lymphoma 2 (BCL-2) and multi-drug resistance associated P-glycoprotein (MDR1) expressions and chemoradiotherapy outcome of patients with non-small cell lung cancer (NSCLC) were analysed.
Thirty-two NSCLC patients were treated with paclitaxel-based chemoradiotherapy. The tumour expressions of BCL-2 and MDR1 were analysed by means of immunohistochemistry with regard to the clinical response and survival data.
Partial remission and stable disease were achieved in 19 (59%) and 10 (31%) cases, respectively. Significant differences in progression-free survival were observed between responders and non-responders (13.7 vs. 6.0 months, p=0.028), and between patients with or without a gross tumour volume (GTV) shrinkage (GTV(>50) 13.7 vs. 6.0 months, p=0.009). Overexpression of BCL-2 and of MDR1 was observed in 6 (21.4%) cases each. Overexpression of both markers together was associated with poor response (GTV reduction: p=0.005; RECIST: p=0.023) and lower progression-free survival (overexpression of both, low expression of both, mixed: 3.1, 13.4, 4.1 months, respectively, p<0.001).
BCL-2 and MDR1 overexpression may predict the inefficacy of paclitaxel-based chemoradiotherapy.
Available from: Yuhchyau Chen
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ABSTRACT: Local and distant failure rates remain high despite aggressive chemoradiation (CRT) treatment for Stage III non-small-cell lung cancer. We conducted preclinical studies of docetaxel's cytotoxic and radiosensitizing effects on lung cancer cell lines and designed a pilot study to target distant micrometastasis upfront with one-cycle induction chemotherapy, followed by low-dose radiosensitizing docetaxel CRT.
A preclinical study was conducted in human lung cancer cell lines NCI 520 and A549. Cells were treated with two concentrations of docetaxel for 3 h and then irradiated immediately or after a 24-h delay. A clonogenic survival assay was conducted and analyzed for cytotoxic effects vs. radiosensitizing effects of docetaxel. A pilot clinical study was designed based on preclinical study findings. Twenty-two patients were enrolled with a median follow-up of 4 years. Induction chemotherapy consisted of 75 mg/m(2) of docetaxel and 75 mg/m(2) of cisplatin on Day 1 and 150 mg/m(2) of recombinant human granulocyte colony-stimulating factor on Days 2 through 10. Concurrent CRT was started 3 to 6 weeks later with twice-weekly docetaxel at 10 to 12 mg/m(2) and daily delayed radiation in 1.8-Gy fractions to 64.5 Gy for gross disease.
The preclinical study showed potent cytotoxic effects of docetaxel and subadditive radiosensitizing effects. Delaying radiation resulted in more cancer cell death. The pilot clinical study resulted in a median survival of 32.6 months for the entire cohort, with 3- and 5-year survival rates of 50% and 19%, respectively, and a distant metastasis-free survival rate of 61% for both 3 and 5 years. A pattern-of-failure analysis showed 75% chest failures and 36% all-distant failures. Therapy was well tolerated with Grade 3 esophagitis observed in 23% of patients.
One-cycle full-dose docetaxel/cisplatin induction chemotherapy with recombinant human granulocyte colony-stimulating factor followed by pulsed low-dose docetaxel CRT is promising with regard to its antitumor activity, low rates of distant failure, and low toxicity, suggesting that this regimen deserves further investigation.
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